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4.75 R & P gears


ashtrans
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Hi Dave, what's the deal? Is the reason that the ring gear is narrower (is it?), meaning it can flex more easily and be pushed away from the pinion. (Cue slipper pad? - could this not solve it?).

Or is it to do with the number of teeth which mesh with the pinion gear at any given moment? (Less teeth = more force per tooth = bang?)

Or something else? Why do you reckon they fail?

I guess 6 wheel drive only shares the torque out further, so that's another sign of it's weakness?

[ By the way - apparently a crate arrived which I guess is from you (I'm abroad at the mo). So thanks for that - bloomin' nice of you to sort me out. Cheers. :) ]

Lots of questions I'm afraid!?! Al.

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Dave,

understood, that looks like my 4.7 :(

BUT... there's plenty of trucks on here have had good success with 4.75s (Read Bros, Tonk, Jez, Ripley,.) so while they might not be the srongest they are better than stock 4.7 and provide excellent gearing with 35" tyres and a 1.2 (or thereabouts) xfer box).

gearing.jpg

For those like me on a tight budget I can upgrade one axle at a time (can't do that with 4.11s) and with the 1.2 xfer box I get a low first ratio of 56:1 and still have the options (without effecting hi gears) of fitting your crawler gears or an underdirve.

So while I would accept a health warning, "not as strong as 3.54", they are clearly in demand and are on the whole performing well.

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Hi Dave, what's the deal? Is the reason that the ring gear is narrower (is it?), meaning it can flex more easily and be pushed away from the pinion. (Cue slipper pad? - could this not solve it?).

Or is it to do with the number of teeth which mesh with the pinion gear at any given moment? (Less teeth = more force per tooth = bang?)

Or something else? Why do you reckon they fail?

I guess 6 wheel drive only shares the torque out further, so that's another sign of it's weakness?

[ By the way - apparently a crate arrived which I guess is from you (I'm abroad at the mo). So thanks for that - bloomin' nice of you to sort me out. Cheers. :) ]

Lots of questions I'm afraid!?! Al.

"Is the reason that the ring gear is narrower (is it?), meaning it can flex more easily and be pushed away from the pinion. (Cue slipper pad? - could this not solve it?)."

the ring gear should be thicker in theory but I guess pegging would have helped,

"Or is it to do with the number of teeth which mesh with the pinion gear at any given moment? (Less teeth = more force per tooth = bang?)"

Yes I think this is more the case

I guess 6 wheel drive only shares the torque out further, so that's another sign of it's weakness?

Yes but this was a strange vehicle, not sure of weight but I think it was well loaded,

[ By the way - apparently a crate arrived which I guess is from you (I'm abroad at the mo). So thanks for that - bloomin' nice of you to sort me out. Cheers. :) ]

No prob but to be honest I don't remember making an invoice out to Astro Al !

"BUT... there's plenty of trucks on here have had good success with 4.75s (Read Bros, Tonk, Jez, Ripley,.) so while they might not be the srongest they are better than stock 4.7 and provide excellent gearing with 35" tyres and a 1.2 (or thereabouts) xfer box)."

definatly better than stock and yes this may have just failed due the vehicle weight, I don't have any details of what it was doing,

"For those like me on a tight budget I can upgrade one axle at a time (can't do that with 4.11s) and with the 1.2 xfer box I get a low first ratio of 56:1 and still have the options (without effecting hi gears) of fitting your crawler gears or an underdirve.

So while I would accept a health warning, "not as strong as 3.54", they are clearly in demand and are on the whole performing well."

agreed, fair comment,

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Hi Dave,

How much just for the kit?

Would save my "crude" plans!

Roger

Hi Roger, I would do a reworked casing at £ 165 + VAT, exchange, this would be for the casing, studs, nots and thrust pad,

Lara, I knew you delt with him, I didn't know he had a Lagonda !

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Hi Roger, I would do a reworked casing at £ 165 + VAT, exchange, this would be for the casing, studs, nots and thrust pad,

Lara, I knew you delt with him, I didn't know he had a Lagonda !

Dave - is there a possibility to buy just the studs, nuts and thrust pad? I think there are people who could happily re-work the casing themselves.

Cheers, Al.

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Dave - is there a possibility to buy just the studs, nuts and thrust pad? I think there are people who could happily re-work the casing themselves.

Cheers, Al.

not sure Al,

2 reasons :

1) the welding is very tricky, you need specific cast iron rods and some serious welding skill to get it right,

and 2) I don't want to see pidgeon s**t welding and oil leaks and someone pointing to it saying it's an Ashcroft kit, load of c**p,

this is not a dig at the DIYer but our welding guy has 35 years experience, a £ 12K TIG machine and we have only found 1 type of rod in the UK that will give a good result.

If the weld is not good, the outer bracket will just crack off when the thrust pad gets a thump,

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not sure Al,

2 reasons :

1) the welding is very tricky, you need specific cast iron rods and some serious welding skill to get it right,

and 2) I don't want to see pidgeon s**t welding and oil leaks and someone pointing to it saying it's an Ashcroft kit, load of c**p,

this is not a dig at the DIYer but our welding guy has 35 years experience, a £ 12K TIG machine and we have only found 1 type of rod in the UK that will give a good result.

If the weld is not good, the outer bracket will just crack off when the thrust pad gets a thump,

Yes sure - that's absolutely understandable as it could reflect on your company. I guess you just have to choose whether it's something you are prepared to supply on the basis that what people do with it - and how proficient the welding is - is entirely the responsibility of the owner.

I honestly don't think anyone with a brain would blame Ashcrofts, when it's obviously nothing to do with you after you supply the bits, but then, not everyone has a brain worth talking about... :( Maybe you've encountered this sort of thing before?

Well, let us know what you decide either way. Cheers, Al.

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Hi, you are right Jules, this is a strange one made with the series 4.7 offset, it is being replaced by one with 3.54 offset like this :

Hi

The one on the left is a Kam 4.75 ring and the one on the right is a standard 90 ring

Hell of a differance

ring1.jpg

In the diffs

newold.JPG

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